Lifting-jack.



No. 758,903. PATENTED MAY 3, 1904. D. DONALD.

LIPTING JACK.

APPLICATION FILED APR. 9. 1903.

UNITED STATES Patented May 3, 1904.

PATEN '1 OFFICE.

LIFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 7 58,903, dated May 3,1904.

Application filed rpril 9, 1903. Serial No. 151,710. (No model.)

To all whom it 71mg concern.-

Be it known that I, DONALD DONALD, a citizen of New Zealand, and aresident of Masterton, New Zealand, have invented certain new and usefulImprovements in Lifting-Jacks, of which the following is aspecification.

This invention relates to improvements in lifting-jacks of that class inwhich a ratchetfaced lifting-bar is mounted to slide vertically within astandard and is given a step by-step motion up or down, as desired, by apair of pawls mounted upon an oscillating fulcrum and serving to engagesuccessive teeth of the bar in alternation as the fulcrum is oscillated.The object of the invention is to provide an improved construction indevices of this character; and it consists of the matters hereinafterset forth, and particularly pointed out in the appended claims.

In the accompanying drawings, Figure 1 is a rear edge elevation of ajack constructed in accordance with my improvement. Fig. 2 is a sideelevation thereof. Fig. 3 is an enlarged sectional detail of theoperative parts of the mechanism, taken on line 3 3 of Fig. A. Fig. 4 isan enlarged sectional detail taken on line 4 4 of Fig. 3. Fig. 5 is aperspective view of the oscillating fulcrum alone, parts being brokenaway. Fig. 6 is a sectional detail taken on line 6 6 of Fig. 2. Fig. 7is a sectional detail showing the manner in which the pawl-pivots aresecured within the oscillating fulcrum. Fig. 8 is a perspective detailof the outside pawl.

In said drawings, A designates the jackframe or standard, and B thetoothed liftingbar, which slides vertically on said standard. As hereinshown, the lifting bar passes through a housing A, formed at the upperend of the standard, and is itself provided at its lower end with prongs7), which embrace ribs (1, that extend vertically up the front edges ofthe standard on each side from its base A to the housing A. Openings (1,cut

through the ribs 7/ above the base, enable the prongs of the lifting-barto be passed in behind the ribs a these openings being afterwardpreferably and desirably filled by wedges a", driven in from the innersides of the ribs.

The housing A is bored out in front of the lifting-bar to receive theoscillating fulcrum C, which carries the pawls D and E. This oscillatingfulcrum is essentially a cylindric part cut away at its upper middleportion to a depth of something more than half the diameter of thecylinder, Fig. 5. This leaves at its ends completely circular diskportions 0, connected below by an integral part c, the lower surface ofwhich is cylindric and coincides with the exterior of the end disks,forming therewith the bearing-surface of the fulcrum. This fulcrumextends entirely through the housing and is provided at one end with apolygonal projecting lug c", to which the operating-handle O of the jackis applied, like an ordinary socket-wrench. Radially-projccting lugs con the outer faces of the ends of the fulcrum serve to loosely embracethe outside of the housing and hold the fulcrum against endwise movementwith reference thereto. These lugs are admitted when the fulcrum isoriginally inserted through apertures a, opening into the bore, whichreceives the fulcrum. The apertures (1 are provided in a differentangular position from that which is occupied by the lugs after themachine is assembled, and the fulcrum is inserted by turning it sothatits lugs 0 will come in line with and pass through the apertures-cand by then turning it back within the housing to bring its bearing-facelowermost. This carries the lugs 0 out of alinement with theextensionopenings (4 even du ring the most extreme normal oscillation ofthe fulcrum, and thus prevents their slipping back through theextension-openings except by intention.

The pawls D and E are carried upon hardened-steel pins F and F in holesbored in the end disk portions 0 of the fulcrum and span, as it were,its cut-away upper middle portion. Such pins are further supportedmidway between their ends by bearings 0", formed on the cut-away upperside of the connecting portion 0 of the fulcrum, the lower ends of thepawls being bifurcated, as shown in Fig. 8. so as to span thebearing-lugs thus provided. To retain the pins F and F in place, theholes which receive them are bored clear through the end disk 0 of thefulcrum at one end, as shown at (1, but are only bored part way throughin the disk 0 at the other end, as shown in Figs. 5 and 7. The pin isthen thrust entirely through the hole 0 and through the hole in the pawluntil it enters and is firmly seated in the hole 0, whereupon the metalaround which the edge of the hole at 0 is jammed in, so as to preventthe pin from sliding out under ordinary circumstances. A small aperture0 extending through the end disk of the fulcrum from the socket 0 thenenables a punch to be inserted for the purpose of driving the pin outwhenever it is desirable to remove the pawls.

An important feature of the present improvement consists in mounting thepin F, which supports the inner pawl D, at a greater distance from theaxis of the oscillating fulcrum than is the pin F, which supports theouter pawl E, Fig. 3. This results in increasing the effective movementof the load during the downstroke, when the weight of the operators bodycan be applied to the operatinghandle, and correspondingly of relativelyincreasing the leverage during the upstroke, when the handle must belifted by main strength. The difference existing in the device hereillustrated is about as five is to three; but this may obviously bevaried as desired and according to the particular class of work forwhich the machine is intended.

The operation of my improved jack in lifting a load requires simply thatthe lever-handle be oscillated, whereupon each pawl will take hold ofthe toothed barin succession as it rises and will drag idly over itsteeth as it descends, thus gradually forcing the bar up to the limit ofits movement. In lowering the load the gravity of the pawls is overcomeby taking hold of them with one hand, while the lever is oscillated withthe other. To this end the inner pawl D is provided on each side withlugs (Z, which project inwardly past the toothed edge of the bar oneither side and not only form finger-pieces, but serve as weights toinsure the engagement of the pawl with the bar by gravity, while theouter pawl E is provided at its upper end with a projecting ear 6, whichcan conveniently be grasped by the thumb, while one of the finger-piecese of the inner pawl is caught by the fingers.

I claim as my invention- 1. A lifting-jack comprising a standard, atoothed bar having a sliding engagement with said standard, and a pairof pawls mounted on an oscillating fulcrum and acting upon the toothedbar in alternation, the pivotal points of said pawls being at differentdistances from the oscillatory axis of the fulcrum, substantially asdescribed.

2. A lifting-jack comprising a standard, a toothed bar having a slidingengagement with said standard, and a pair of pawls mounted on anoscillating fulcrum and acting upon the toothed bar in alternation, thepivotal point of the inner pawl being at a greater distance from theoscillatory axis of the fulcrum than the pivotal point of the outerpawl, substantially as described. 7

3. A lifting-jack comprising a standard, a toothed bar having slidingengagement with said standard, an oscillatory fulcrum mounted in thestandard, and a pair of pawls pivoted to said fulcrum and acting uponthe toothed bar in alternation, said fulcrum comprising cylindric enddisks connected below by an intermediate part, pivot pins for the pawlsmounted in apertures in said end disks, and bearing lugs on the integralconnecting part for the middle of said pin, substantially as de-.scribed.

4. A lifting-jack comprising a standard, a toothed bar having slidingengagement with said standard, an oscillatory fulcrum inserted through abore in the standard, and a pair of pawls pivoted to said fulcrum andacting upon the toothed bar in alternation, said fulcrum being providedat its ends with lugs embracing the sides of the standards to preventendwise movement of the fulcrum, and said standard being provided withapertures at the edge of its fulcrum-receiving bore for admitting saidradial lugs,'substantially as described.

In testimony that I claim the foregoing as my invention I aflix mysignature, in presence of two subscribing witnesses, this 7th day ofApril, A. D. 1903.

DONALD DONALD. Witnesses:

HENRY W. CARTER, R. A. Cos'rELLo.

